Python Programming | JNTUK | UNIT 1 | Lecture 5
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This document provides an overview of the topics covered in Unit 1 of a Python programming syllabus. It includes introductions to computer science topics, computer systems, installing Python, basic syntax, data types, variables, arithmetic operators, expressions, comments, and understanding error messages. Example code and explanations of operators like arithmetic, assignment, comparison, logical, membership, identity, and bitwise are also provided.
Python Programming | JNTUK | UNIT 1 | Lecture 5
- 2. UNIT 1 : SYLLABUS • Conceptual introduction: topics in computer science, algorithms; • Modern computer systems: hardware architecture, data representation in computers, software and operating system; • Installing Python; basic syntax, interactive shell, editing, saving, and running a script. • The concept of data types; variables, assignments; immutable variables; numerical types; • arithmetic operators and expressions; comments in the program; understanding error messages;
- 5. Operators Arithmetic operators: EXPRESSION RESULT 10 + 20 30 40 - 15 25 15 * 10 150 25 / 5 5.0 5 ** 2 25 15 % 2 1 9 // 2 4 9.0 // 2.0 4.0 -11 // 3 - 4 -11.0 // 3 - 4.0 OPERATOR MEANING + Addition - Subtraction * Multiplication / Division ** Exponent % Modulus // Floor Division
- 6. Operators Assignment operators: • There are two types of assignment statements in Python. They are: 1. Basic assignment statements 2. Augmented assignment statements • The simple syntax for a basic assignment statement is: variable_name = expression • Ex : a = 2 +3 a = a + 2
- 7. Operators • There are two types of assignment statements in Python. They are: 1. Basic assignment statements 2. Augmented assignment statements • We can combine arithmetic operators in assignments to form an augmented assignment statement. a = a + b is written as a + = b • Here the left-hand side i.e., a is evaluated first, then value of b is evaluated and then addition is performed, and finally the addition result is written back to a x = x * 2 is written as x * = 2
- 8. Operators OPERATOR EXAMPLE SAME AS = X = 5 X = 5 += X + = 3 X = X + 3 -+ X - = 3 X = X – 3 *= X * = 3 X = X * 3 /= X / = 3 X = X / 3 %= X % = 3 X = X % 3 //= X //= 3 X = X // 3 **= X ** = 3 X = X ** 3
- 9. Operators Comparison operators: • Comparison operators are used to compare two values: EX: X = 3, Y = 4, Z = 4 X == Y Output: False Y == Z Output: True OPERATOR MEANING EXAMPLE == Equal X == Y != Not Equal X != Y > Greater than X > Y < Less Than X < Y >= Greater than or Equal to X > = Y <= Less Than or Equal to X < =Y
- 10. Operators Logical operators: • Logical operators are used to combine conditional statements: OPERATOR DESCRIPTION EXAMPLE and Returns True if both statements are true x < 5 and x < 10 or Returns True if one of the statements is true x < 5 or x < 4 not Reverse the result, returns False if the result is true not(x < 5 and x < 10)
- 11. Operators Identity operators: • Identity operators are used to compare the objects, not if they are equal, but if they are the same object, with the same memory location: OPERATOR DESCRIPTION EXAMPLE is Returns True if both variables are the same object x is y is not Returns True if both variables are not the same object x is not y
- 12. Operators Membership operators: • Membership operators are used to test if a sequence is presented in an object: OPERATOR DESCRIPTION EXAMPLE in Returns True if a sequence with the specified value is present in the object x in y not in Returns True if a sequence with the specified value is not present in the object x not in y
- 13. Operators Bitwise operators: • Bitwise operators are used to compare (binary) numbers: OPERATOR MEANING DESCRIPTION & AND Sets each bit to 1 if both bits are 1 | OR Sets each bit to 1 if one of two bits is 1 ^ XOR Sets each bit to 1 if only one of two bits is 1 - NOT Inverts all the bits << Zero fill left shift Shift left by pushing zeros in from the right and let the leftmost bits fall off >> Signed right shift Shift right by pushing copies of the leftmost bit in from the left, and let the rightmost bits fall off
- 16. Expressions • An expression is a combination of values(Constants), variables and operators. • Instructions that a Python interpreter can execute are called statements. For example, a = 1 is an assignment statement. • a = 10 # This is an assignment statement • b = 10 # This is an assignment statement • print(a + b) o # a + b is an expression o print(a + b) is a statement • a = b * 5 + c o # b * 5 + c is an expression o a = b * 5 + c is a statement
- 17. Consider a=1, b=5, c=6, d=3. Evaluate b – a * c / d + 10 Answer : 13
- 18. Expressions
- 20. Comments • A comment is a piece of program text that the computer ignores but that provides useful documentation to programmers. • # symbol is used to add comments. a = 10 # a value assigned b = 20 # b value assigned c = a + b # sum of a and b assigned to c
- 22. Error Messages How Python Works: • In python there are three types of errors; o Syntax errors o Semantic errors o Exceptions
- 23. Error Messages • The most common reason of an error in a Python program is when a certain statement is not in accordance with the prescribed usage. Such an error is called a syntax error. • When Python encounters a syntax error in a program, it halts execution with an error message.
- 24. Error Messages • A semantic error is detected when the action that an expression describes cannot be carried out, even though that expression is syntactically correct.
- 26. UNIT 1 : SYLLABUS • Conceptual introduction: topics in computer science, algorithms; • Modern computer systems: hardware architecture, data representation in computers, software and operating system; • Installing Python; basic syntax, interactive shell, editing, saving, and running a script. • The concept of data types; variables, assignments; immutable variables; numerical types; • arithmetic operators and expressions; comments in the program; understanding error messages;